JP2790334B2 - Multi-layer structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Industrial Field of the Invention The present invention has excellent heat stability and melt moldability comprising a mixture of a polyamide resin, an ethylene-vinyl alcohol copolymer (EVOH) and a third component. The present invention relates to a multilayer structure comprising at least two layers of a resin composition layer and a rubber layer. Such a resin composition is excellent in rubber and lamination processability,
It is suitable for supplying a molded product suitable for imparting a barrier property without impairing the flexibility of rubber even when laminated.

B. Conventional technology (1): EVOH has excellent melt moldability, gas barrier properties, fragrance retention, oil / solvent resistance, and antistatic properties, and polyamide resin has impact resistance, flexibility, and high temperature and humidity. Because of its excellent heat properties, molded articles comprising a composition in which both are mixed have been proposed for use as films, sheets, and bottles for food packaging, medicine, and agricultural chemicals.

However, as is well known, the thermal stability of both polyamide resin and EVOH is poor, and there is a problem of gelation when molding is continued for a long time. However, in the case of a mixture of polyamide resin and EVOH, this is further accelerated, and the molding is started for several hours. You may see gel formation later. Furthermore, a mixture of a polyamide resin and EVOH has a ratio of the number of methylene groups to the number of amide groups of 9 ≦ CH.
The polyamide resin of ₂ / NHCO has a large die swell at the time of molding, and therefore has a problem of poor melt moldability such as an increase in thickness unevenness of a film or a sheet. Therefore, improvement is demanded.

As a method for improving thermal stability, a proposal has been made to increase the ratio of carboxyl groups and amide groups at the terminal of the polyamide to an excess of carboxyl groups, but it is difficult to sufficiently increase the ratio of carboxyl groups in the production of polyamide. The required effect of improving thermal stability has not yet been obtained. On the other hand, there is no known technique for improving melt formability.

(Part 2): Conventionally, Freon hose for automobile air conditioner,
For applications requiring flexibility and gas barrier properties, such as diaphragms for expansion tanks for hot water supply and cooling / heating systems, rubber products with excellent gas barrier properties such as acrylonitrile-butadiene copolymer rubber (NBR) and butyl rubber have been used. However, in recent years, various fields have come to a situation where rubber alone cannot cope. For example, for Freon hoses, it is essential to reduce gas leakage from hoses in order to prevent the destruction of the stratospheric ozone layer by Freon gas. Although it is said that it is necessary to reduce it below, NBR and other rubber hoses cannot be used. Conventionally, butyl rubber is used for the diaphragm of the expansion tank of the hot water supply and cooling / heating systems, and the pressure of the nitrogen gas decreases with time, so the nitrogen gas can be adjusted every several months to one year. Although it is necessary, the use of this type of expansion tank has been growing rapidly in recent years. It is necessary to reduce it to 1/5 to 1/10 or less.

As a method of improving the barrier properties of rubber, it is easily conceived to combine rubber and gas barrier resin, and the use of various barrier resins has been proposed, and some proposals have also been made regarding the use of EVOH or nylon. Can be seen. For example, JP-A-58-197040, JP-A-60-18331, and JP-B-62-29242 disclose that EVOH is laminated with rubber in a single layer or in a multilayer with a polyamide or other resin. Is used alone and is inferior in low-temperature strength, low-temperature flexibility, and high-temperature wet heat resistance. JP-A-53-63
614 proposes laminating a mixture of EVOH and polyamide with rubber, but the examples only describe EVOH alone or a blend of EVOH and modified polyethylene. Furthermore, JP-B-44-24277 or JP-A-50-121347
Discloses a blend of EVOH and polyamide, but all publications describe the use of 6-nylon, but there is no description of 11-nylon or 12-nylon in the specification and examples. In addition, EVOH and 6-nylon systems tend to generate gel during molding, and are inferior in flexibility and high-temperature wet heat resistance.

In addition, JP-A-63-114645 discloses a blend of a nylon resin and EVOH in which the ratio of the number of methylene groups to the number of amide groups satisfies 6.6 ≦ CH ₂ / NHCO ≦ 10, but this configuration has insufficient flexibility. It is.

C. Problems to be Solved by the Invention <First Problem> The conventional technology for mixing EVOH and polyamide resin does not sufficiently solve the thermal stability, and it is not clear how to solve the melt molding failure. This solution is the first object of the present invention.

<Second Problem> A second problem of the present invention is to provide flexibility, for example, by combining a mixture of EVOH and polyamide with rubber to improve gas barrier properties without impairing the flexibility of rubber. is there.

D. Means for Solving the Problem The means for solving the first problem is that (A) polyamide resin and (B) EVOH are added to (C) aromatic acid amide, aromatic acid ester and olefin-based elastomer. It is to mix at least one selected.

Means for solving the first and second problems is to select 11-nylon and / or 12-nylon as the polyamide resin (A), and blend (B) and (C) with it. That is.

Next, details of the means for solving the first problem will be described.

(B) EVOH used in the present invention has an ethylene content of 20%.
6565 mol%, preferably 25-50 mol%, the degree of saponification of the vinyl acetate moiety is 95 mol% or more, preferably 99.0 mol% or more. If the ethylene content is less than 20 mol%, the gas barrier property at high humidity decreases, and if it exceeds 65 mol%, the gas barrier property also decreases. The degree of saponification is 95 mol%
If it is less than this, the gas barrier property also decreases. Also EVOH
Melt index (MI) (at 190 ℃, under 2160g load)
0.5-20 g / 10 min is preferred.

The polyamide resin (A) used in the present invention includes nylon 6, nylon 10, nylon 11, nylon 12, nylon 6.6, nylon 6.9, nylon 610, nylon 6.11, nylon 6.12, and nylon. 6/6 ・ 6, nylon 1
One or a mixture of two or more selected from 2, 12, etc. can be used.

The mixing ratio {(A) / (B)} of (A) polyamide resin and (B) EVOH in the present invention is 95/5 to 5/95 by weight,
Preferably it is 10/90 to 80/20, more preferably 25/75 to 70/30.
If the mixing ratio of EVOH is less than 5%, the gas barrier properties will be insufficient.
On the other hand, if the mixing ratio of the nylon resin is less than 5%, the impact resistance is improved.
Poor flexibility.

The present invention is characterized in that an aromatic acid amide, or an aromatic acid ester, or a polyolefin-based elastomer is mixed and used as the third component.By mixing these third components, EVOH and the polyamide resin are mixed for the first time. Poor thermal stability and / or poor melt moldability of the mixture,
That is, gel generation and / or thickness variation can be solved.

As the aromatic acid amide or aromatic acid ester (C) used in the present invention, benzenesulfonic acid amides and derivatives thereof such as benzenesulfonic acid ethylamide and benzenesulfonic acid butylamide, or benzoic acid ethylamide, benzoic acid butylamide and benzoic acid 2 Benzoic acid amides such as ethylhexylamide and derivatives thereof,
Or methyl benzoate, ethyl benzoate, benzoic acid 2
Benzoic acid esters such as ethylhexyl and derivatives thereof can be used, with a boiling point of 160 ° C or higher / 2mmHg
Are preferred.

As the olefin-based elastomer of the present invention, a copolymer of ethylene and propylene (EPM), a copolymer of ethylene and propylene and a diene monomer (EPDM), or a mixture of these copolymers with polyethylene or polypropylene is used. it can.

In the present invention, the weight ratio of the third component (C) to the total weight of (A) EVOH and (B) the polyamide resin is Δ (A) +
(B)｝ / (C) = 100/2 to 100/40. If the weight ratio of the third component is less than 2/100, poor heat stability and / or poor melt moldability will not be improved, and if the weight ratio exceeds 40/100, the barrier properties will be insufficient.

The reason that the mixing of these third components improves the thermal stability of EVOH and the polyamide resin and the mixed melt moldability is mainly due to the improvement of the compatibility between the EVOH and the polyamide resin for aromatic acid amides and aromatic acid esters. It is presumed that the polyolefin elastomer is mainly due to the effect of reducing the reaction between EVOH and the polyamide resin.

Next, details of means for solving the first and second problems of the present invention will be described.

The present inventors have studied a mixture of 11-nylon or 12-nylon and EVOH having excellent gas barrier properties in order to solve the above problems. 11-nylon and 12-nylon are excellent in flexibility and high-temperature wet heat resistance, but are inferior in gas barrier properties. On the other hand, EVOH has excellent gas barrier properties, but is inferior in flexibility and high-temperature wet heat resistance. Therefore, by mixing 11-nylon or 12-nylon with EVOH, it is expected that excellent physical properties which complement the respective disadvantages will be obtained. However, as is well known, mixing and melting a nylon resin and EVOH has a drawback in that thermal stability is poor, such as generation of a gel, and cannot be operated for a long time.In addition, mixing of 11-nylon or 12-nylon with EVOH has an additional problem. Due to the large die swell, tubes or sheets,
Or, there is a problem that the thickness of the film is fluctuated in the longitudinal direction in the film forming. Accordingly, the present inventor has conducted intensive studies on such poor melt moldability, that is, the improvement of gel formation and thickness fluctuation, and as a result, further mixing a specific third component with 11-nylon or a mixture of 12-nylon and EVOH. And found that the present invention was completed.

That is, the first and second objects of the present invention are (A) 11
The problem is solved by blending at least one selected from (C) aromatic aromatic amides, aromatic acid esters and olefin-based elastomers with at least one selected from nylon and 12-nylon and (B) EVOH. .

Here, as 11-nylon or 12-nylon,
Aminoundecanoic acid, ω-aminododecanoic acid or ω
-Homopolymers and copolymers of laurolactam, or 12.12 nylon. These nylon resins are mainly used alone, but may be mixed.

The mixing ratio of (A) / (B) and {(A) + (B)} / (C) is as described above.

As a method for melt-molding the resin composition of the present invention, methods such as extrusion inflation film formation, extrusion cast film formation, T-die sheet molding, tube molding, compression molding, injection molding, and transfer molding can be used.

Regarding the mixing of (A) EVOH, (B) polyamide resin and (C) third component, any method can be adopted as long as the three components are mixed prior to molding, but (A) +
(B) + (C) is formed after being melt-mixed and pelletized, or (A) + (C) is melt-mixed and then mixed with the pellet of (B), or (B) + (C) )
It is preferable to mix the melt-mixed pellets of (A) and the pellets of (A) before molding.

The molding temperature is preferably 180-260 ° C, preferably 200-240 ° C
It is. If it exceeds 260 ° C., volatilization of the aromatic acid amide or aromatic acid ester occurs, which is not preferable. If necessary, the composition of the present invention may be a carboxylic acid-modified polyolefin, an ethylene-vinyl acetate copolymer having a vinyl acetate content of 3 to 40% by weight (EV) as long as the gas barrier property is not impaired.
A), EVA saponified substances and the like may be added.

Molded articles made of the resin composition of the present invention have excellent gas barrier properties, flexibility, impact resistance, and high-temperature wet heat resistance, and are used as sheets, films, tubes, bottles, containers, and various molded articles. The layer can be used in the fields of food, medicine, industrial goods, etc.

(A) A molded article comprising the resin composition of the present invention using 11-nylon or 12-nylon as a polyamide resin,
It is flexible and has excellent gas barrier properties and high-temperature, high-humidity and heat resistance.
It is mainly used in combination with rubber such as an inner layer tube of a freon hose or an intermediate layer of a diaphragm, but other uses are of course possible.

The vulcanization of rubber is generally carried out by steam heating at 150 to 180 ° C. for about 4 to 6 hours, but the molded article made of the resin composition of the present invention is extremely excellent in high-temperature wet heat resistance,
No melting deformation is observed even after vulcanization.

As long as the multilayer structure of the present invention does not impair flexibility,
Of course, it can be used in multiple layers with various resins such as 11- or 12-nylon. Coextrusion molding, lamination processing, etc. can be used for multilayering.

 Next, the multilayer structure of the present invention will be further described by way of examples.

E. Examples Example 1 Ethylene content 32.0 mol%, degree of saponification 99.6 mol%, MI
(At 190 ° C, under 2160g load) 1.3g / 10min EVOH 70 parts by weight and 12
-Using a pelletizer consisting of an extruder (4 mmφ, L / D = 28), a die, a cooling water tank, and a cutter, while adding 6 parts by weight of benzenesulfonic acid butylamide to a mixed pellet of 30 parts by weight of nylon with an extruder hopper. At 230 ° C. to form a melt-mixed pellet. The pellet forming was smooth, and the thickness of the strand discharged from the die was uniform in the flow direction. Using this pellet, an extruder (40 mmφ, L / D = 2
8) A film having a thickness of 50 μm was formed at an extrusion temperature of 230 ° C. using a film forming machine including a T-die and a take-off machine. The film preparation was smooth without thickness fluctuation and gel generation. The oxygen permeability of this film was measured at 20 ° C. and 65% RH using OXTRAN 10 / 50A manufactured by Modern Control Co. and found to be 2.5 cc · 20 μ / m ² · day · atm.

The 12-nylon single film used had an oxygen permeability of 7,800 cc · 20 μ / m ² · day · atm.

Comparative Example 1 Ethylene content 32.0 mol%, saponification degree 99.6 mol%, MI
A tumbler mixed pellet of 70 parts by weight of EVOH pellet and 30 parts by weight of 12-nylon pellet at 1.3 g / 10 min (at 190 ° C. under a load of 2160 g) was pelletized at an extrusion temperature of 230 ° C. in the same apparatus as in Example 1. I got it. The thickness of the strand taken from the die fluctuates in the flow direction, and the strand breaks frequently,
It was difficult to achieve continuity. Example 1 using this pellet
When a 50-μm film was prepared using the same equipment as described above, continuous film formation was possible, but the resulting film was found to be gelless and had thickness fluctuations in the flow direction, and was of no commercial value. Was.

Example 2 Ethylene content 44.5 mol%, degree of saponification 99.5 mol%, MI
(At 190 ° C, under 2160g load) 5.5g / 10min EVOH 50 parts by weight, 6
12 copolymerized nylon (copolymerization ratio: 6/12 = 90/10) To a tumbler-mixed pellet of 50 parts by weight, 4 parts by weight of 2-ethylhexyl paraoxybenzoate was added by an extruder hopper, and the same apparatus as in Example 1 was used. Pelletization was performed under the conditions. The pellet forming was smooth, and the thickness of the strand discharged from the die was uniform in the flow direction. Using this pellet, a film was formed under the same conditions as in Example 1 under the same conditions. The film preparation was smooth without thickness fluctuation and gel generation.
When the oxygen transmission rate was measured in the same manner as in Example 1, 18.6 cc
・ It was 20μ / m ²・ day ・ atm.

The oxygen permeation rate of the used 6/12 copolymer nylon film was 240 cc · 20 μ / m ² · day · atm.

Example 3 Ethylene content 47.5 mol%, degree of saponification 99.6 mol%, MI
(Under 190 ° C, 2160g load) 80g by weight of EVOH, 14g / 10min, 6-
A tumbler mixed pellet of 20 parts by weight of nylon and 25 parts by weight of ethylene-propylene copolymer rubber was pelletized at 250 ° C. in the same apparatus as in Example 1. The pellet forming was smooth, and the thickness of the strand discharged from the die was uniform in the flow direction. Using this pellet, a 50 μm film was formed at an extrusion temperature of 250 ° C. using the same film forming machine as in Example 1. The film was good without any discoloration, no thickness fluctuation and no gel generation. The resulting film had an oxygen permeability of 7.3 cc.20 μ / m ² .day.atm.

The 6-nylon single film used had an oxygen permeability of 130 cc · 20 μ / m ² · day · atm.

Comparative Example 2 Pelletization was carried out by removing the ethylene-propylene copolymer rubber from Example 3. Although the strand was yellowed, there was no unevenness in the thickness in the flow direction, and the pick-up was smooth.
Using this pellet, a 50 μm film was formed using the same apparatus as in Example 1. As a result, yellowing further advanced and a gel was observed.

Example 4 ω-Laurolactam ring-opened polymer 12-nylon 60 parts by weight, ethylene content 32.0 mol%, saponification degree 99.6 mol%,
MI (190 ° C, 2160g load measurement) 1.3g / 10min EVOH 40 parts by weight mixed benzenesulfonic acid butylamide 6
While adding parts by weight from the extruder hopper, the extruder (40mm
φ, L / D = 28), using a pelletizing device consisting of a die, a cooling water tank, and a take-off cutter, the mixture was melted and mixed at 230 ° C. The pellet forming was smooth, and the thickness of the strand discharged from the die was uniform in the flow direction. Using this pellet, a film having a thickness of 300 μm was formed at an extrusion temperature of 230 ° C. using a film forming machine including an extruder (40 mmφ, L / D = 28), a T-die, and a take-off machine. The film preparation was smooth without thickness fluctuation and gel generation.

Using this film and a control, butyl rubber having a thickness of 300 μm and NBR having a thickness of 860 μm, the nitrogen gas permeability at 35 ° C. (cc · 20 μ / m ² · day ·) was determined in accordance with ASTM D1434.
atm), Perfluorocarbon 12 gas permeability at 70 ° C (cc · 20μ / m ²
・ Day ・ atm), the following results were obtained.

Using this film, a non-vulcanized butyl rubber molded product was bonded to both sides of a product molded into a predetermined shape by a vacuum thermoforming machine, and then vulcanized at 150 ° C for 4 hours to obtain a diaphragm for swelling tank (average total volume). A thickness of 1.0 mm and an intermediate layer film average thickness of 75 μm) were prepared. The obtained diaphragm has almost the same flexibility as the diaphragm of butyl rubber alone, and the gas permeability is improved to about 1/6.

Example 5 Using a pellet having the same composition as in Example 4, an extruder (40
mmφ, L / D = 26), using a tube forming machine consisting of a circular die, a sizing device, a cooling device and a take-off device.
The mixture was melted and mixed at 230 ° C. to prepare a tube having an outer diameter of 12.5 mmφ and a wall thickness of 500 μm. Tube making is smooth without thickness fluctuation,
No gel was generated. An NBR layer reinforced by braiding was formed on the outer layer of the tube, and vulcanization treatment was performed by steam heating to prepare a freon hose having a total thickness of 5.0 mm. No melt denaturation was observed in the inner tube layer. This hose had almost the same flexibility as the hose without the tube. Next, when the permeation amount of Freon 12 gas at 100 ° C. for 72 hours was compared in accordance with ASTM D 1680, the tube-incorporated hose had a permeation amount of 1/12 of the hose not incorporating the tube.

Example 6 ω-Laurolactam ring-opened polymer 12-nylon 40 parts by weight, ethylene content 44.2 mol%, saponification degree 99.5 mol%,
MI (190 ° C., 2160 g load measurement) 5.5 g / 10 min EVOH 60 parts by weight and ethylene-propylene copolymer rubber 30 parts by weight were tumbled and mixed at 220 ° C. using the same pelletizer as in Example 4. Was done. Forming was smooth and the thickness of the strand discharged from the die was uniform in the flow direction. Using this pellet, a film having a thickness of 50 μm was formed at an extrusion temperature of 220 ° C. using the same film forming machine as in Example 4. The film preparation was smooth without thickness fluctuation and gel generation. The gas permeability of the obtained film was excellent as follows.

Example 7 11-nylon of a condensation polymer of ω-aminoundecanoic acid
A melt-mixed pellet of 60 parts by weight and 10 parts by weight of 2-ethylhexyl paraoxybenzoate, ethylene content 32.0 mol%, saponification degree 99.6 mol%, MI (190 ° C, 2160g load measurement) 1.3g / 10
The tumbler mixture of 40 parts by weight of the EVOH pellet was melt-mixed and pelletized at 220 ° C. in the same pelletizer as in Example 4. The strand molding was smooth, and the thickness of the strand discharged from the die was uniform in the flow direction.
Using this pellet, a film having a thickness of 50 μm was formed at an extrusion temperature of 220 ° C. using the same film forming machine as in Example 4. The film preparation was smooth without thickness fluctuation and gel generation. The gas permeability of the obtained film was as follows.

Comparative Example 3 11-nylon of a condensation polymer of ω-aminoundecanoic acid
A tumbler mixed pellet of 60 parts by weight, an ethylene content of 32.0 mol%, a saponification degree of 99.6 mol%, and an MI (190 ° C., 2160 g load measurement) 1.3 g / 10 min. When the melt-mixed pellet was formed at a temperature of ° C., the thickness of the strand discharged from the die fluctuated in the flow direction, the strand was frequently cut, and continuation was difficult. Using this pellet, an attempt was made to produce a 50 μm thick film at an extrusion temperature of 220 ° C. using the same film forming machine as in Example 4. As a result, continuous production of the film was possible, but the obtained film was thick and thin. The gel was recognized and had no commercial value.

Comparative Example 4 Using the same film forming machine as in Example 4,
Film formation was performed using 12-nylon alone to obtain a film having a thickness of 300 μm. The gas permeability of this film was low as shown in the table below.

Comparative Example 5 Using the same film forming machine as in Example 4,
A single film was formed using EVOH to obtain a film having a thickness of 300 μm. Film formation was smooth, and a gel-free film having a uniform thickness was obtained. Although the gas barrier properties of this film were excellent as described below, it was expected that the film would be extremely hard and would impair the flexibility of the rubber. 1mm thick on both sides of this film
When unvulcanized NBR was pasted and steam vulcanized, the EVOH layer was melted and deformed, resulting in uneven thickness.

F. Effects of the Invention The resin composition used in the multilayer structure of the present invention is excellent in melt moldability, excellent in gas barrier properties, excellent in high-temperature wet heat resistance, and 11-nylon and 12-
Molded articles obtained using nylon are flexible and are particularly excellent in laminating with rubber to improve the gas barrier properties of rubber.

Continuation of the front page (51) Int.Cl. ⁶ identification code FI C08L 77/00 C08L 77/00 (58) Field surveyed (Int.Cl. ⁶ , DB name) C08L 23/00-23/36

Claims (1)

(57) [Claims] (1) a polyamide resin, (B) ethylene-
A multilayer structure comprising at least two layers of a layer comprising a resin composition comprising at least one selected from a vinyl alcohol copolymer and (C) an aromatic amide, an aromatic ester and an olefin elastomer, and a rubber layer.